Answer:
 The ladder from the base of the building is 5.18 ft (Approx) 
Explanation:
As given 
A ladder that is 20 ft. Long is leaning against the side of a building. 
If the angle formed between the ladder and the ground is 75. 
 Now using the trignometric property .

As shown in the figure.
 
 
Base = CB
Hypotenuse = AC = 20 ft.
Put in the trignometric identity .



Put in the above


CB = 0.259 × 20
CB = 5.18 ft (Approx)
Therefore the ladder from the base of the building is 5.18 ft (Approx) .